[sishow]

if you have a long term visa you will be ok for a single flight, otherwise you need a return ticket/on ward journey. Otherwise the airline can (and will) stop you boarding or immigration will not allow you in. That be the law.

Of course it can depend on the flight crew + immigration officals. If they notice. But on my last trip, for the first time immigration was asking everyone for there return/onward flight details i.e. my eticket home.